[libvirt] RFC: virInterface change transaction API

[Daniel P. Berrange]

On Mon, Apr 18, 2011 at 12:25:21PM -0400, Laine Stump wrote:
> On 04/14/2011 09:03 AM, Dan Kenigsberg wrote:
> >>3) initscript
> >>
> >>    This initscript will at first live in (be installed by) netcf
> >>    (called /etc/init.d/networking-config?), but hopefully it will
> >>    eventually be accepted by the initscripts package (which includes
> >>    the networking-related initscripts), as it is of general use. (Dan
> >>    Kenigsberg already already took a stab at this script last year,
> >>    but received no reply from the initscripts maintainers, implying
> >>    they may not be too keen on the idea right now - it might take some
> >>    convincing ;-)
> >>
> >>https://fedorahosted.org/pipermail/initscripts-devel/2010-February/000025.html
> >>
> >>    It will have three commands, one of which will be called
> >>    automatically by "start" (the command called automatically at boot
> >>    time):
> >>
> >>    snapshot_config
> >>
> >>      This will save a copy of (what the script believes are - is this
> >>      problematic?) all network-config related files. It may or may not
> >>      be called by netcf (see the notes in ncf_start_change() above.
> >>
> >>      If this function finds that a snapshot has already been taken,
> >>      it should fail.
> >>
> >>
> >>    rollback_config (automatically called from "start" at boottime)
> >>
> >>      This will move back (from the saved copies) all files that were
> >>      changed/removed since snapshot, *and delete any files that have
> >>      been added*.
> >>
> >>      Note that this command doesn't need to worry about ifup/ifdown,
> >>      because it will be called prior to any other networking startup
> >>      (part of the reason that netcf will need to deal with that).
> >>
> >>      I notice that Dan K's version saves the modified files to a
> >>      "rollback-${date}" directory. Does this seem like a good idea?
> >>      It's nice to not lose anything, but there is no provision for
> >>      eliminating old versions, so it could grow without bound.
> >I sleep better at night when there are backups... Obviously, I should not have
> >kept them beyond a certain limit (last 20). And I'd understand if you think that
> >it is the business of a backup system, or conf management system, to take theses
> >backups.
> 
> 
> I'm agnostic. Anyone else have an opinion? Does there need to be a
> method in the API to get to these backups? Or are they just there
> for manual intervention in the case of a catastrophe?

I think we're getting into overkill myself. Best to concentrate of
getting the basic functionality present & working. If someone decides
we need to extend this work to handle historical snapshots of the
interface config we can deal with it later.

Regards,
Daniel
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